libexec/rtld-elf/rtld.h

   1 /*-
   2  * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  * $FreeBSD: src/libexec/rtld-elf/rtld.h,v 1.50 2011/02/09 09:20:27 kib Exp $
  26  */
  27
  28 #ifndef RTLD_H /* { */
  29 #define RTLD_H 1
  30
  31 #include <machine/elf.h>
  32 #include <sys/types.h>
  33 #include <sys/queue.h>
  34
  35 #include <elf-hints.h>
  36 #include <link.h>
  37 #include <setjmp.h>
  38 #include <stddef.h>
  39
  40 #include "rtld_lock.h"
  41 #include "rtld_machdep.h"
  42
  43 #ifndef STANDARD_LIBRARY_PATH
  44 #define STANDARD_LIBRARY_PATH   "/usr/lib"
  45 #endif
  46
  47 #define NEW(type)       ((type *) xmalloc(sizeof(type)))
  48 #define CNEW(type)      ((type *) xcalloc(sizeof(type)))
  49
  50 /* We might as well do booleans like C++. */
  51 typedef unsigned char bool;
  52 #define false   0
  53 #define true    1
  54
  55 extern size_t tls_last_offset;
  56 extern size_t tls_last_size;
  57 extern size_t tls_static_space;
  58 extern int tls_dtv_generation;
  59 extern int tls_max_index;
  60
  61 struct stat;
  62 struct Struct_Obj_Entry;
  63
  64 /* Lists of shared objects */
  65 typedef struct Struct_Objlist_Entry {
  66     STAILQ_ENTRY(Struct_Objlist_Entry) link;
  67     struct Struct_Obj_Entry *obj;
  68 } Objlist_Entry;
  69
  70 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
  71
  72 /* Types of init and fini functions */
  73 typedef void (*InitFunc)(void);
  74
  75 /* Lists of shared object dependencies */
  76 typedef struct Struct_Needed_Entry {
  77     struct Struct_Needed_Entry *next;
  78     struct Struct_Obj_Entry *obj;
  79     unsigned long name;         /* Offset of name in string table */
  80 } Needed_Entry;
  81
  82 typedef struct Struct_Name_Entry {
  83     STAILQ_ENTRY(Struct_Name_Entry) link;
  84     char   name[1];
  85 } Name_Entry;
  86
  87 /* Lock object */
  88 typedef struct Struct_LockInfo {
  89     void *context;              /* Client context for creating locks */
  90     void *thelock;              /* The one big lock */
  91     /* Debugging aids. */
  92     volatile int rcount;        /* Number of readers holding lock */
  93     volatile int wcount;        /* Number of writers holding lock */
  94     /* Methods */
  95     void *(*lock_create)(void *context);
  96     void (*rlock_acquire)(void *lock);
  97     void (*wlock_acquire)(void *lock);
  98     void (*rlock_release)(void *lock);
  99     void (*wlock_release)(void *lock);
 100     void (*lock_destroy)(void *lock);
 101     void (*context_destroy)(void *context);
 102 } LockInfo;
 103
 104 typedef struct Struct_Ver_Entry {
 105         Elf_Word     hash;
 106         unsigned int flags;
 107         const char  *name;
 108         const char  *file;
 109 } Ver_Entry;
 110
 111 #define VER_INFO_HIDDEN 0x01
 112
 113 /*
 114  * Shared object descriptor.
 115  *
 116  * Items marked with "(%)" are dynamically allocated, and must be freed
 117  * when the structure is destroyed.
 118  *
 119  * CAUTION: It appears that the JDK port peeks into these structures.
 120  * It looks at "next" and "mapbase" at least.  Don't add new members
 121  * near the front, until this can be straightened out.
 122  */
 123 typedef struct Struct_Obj_Entry {
 124     /*
 125      * These two items have to be set right for compatibility with the
 126      * original ElfKit crt1.o.
 127      */
 128     Elf_Size magic;             /* Magic number (sanity check) */
 129     Elf_Size version;           /* Version number of struct format */
 130
 131     struct Struct_Obj_Entry *next;
 132     char *path;                 /* Pathname of underlying file (%) */
 133     char *origin_path;          /* Directory path of origin file */
 134     int refcount;
 135     int dl_refcount;            /* Number of times loaded by dlopen */
 136
 137     /* These items are computed by map_object() or by digest_phdr(). */
 138     caddr_t mapbase;            /* Base address of mapped region */
 139     size_t mapsize;             /* Size of mapped region in bytes */
 140     size_t textsize;            /* Size of text segment in bytes */
 141     Elf_Addr vaddrbase;         /* Base address in shared object file */
 142     caddr_t relocbase;          /* Relocation constant = mapbase - vaddrbase */
 143     const Elf_Dyn *dynamic;     /* Dynamic section */
 144     caddr_t entry;              /* Entry point */
 145     const Elf_Phdr *phdr;       /* Program header if it is mapped, else NULL */
 146     size_t phsize;              /* Size of program header in bytes */
 147     const char *interp;         /* Pathname of the interpreter, if any */
 148     caddr_t relro_page;         /* Address of first page of read-only data */
 149     size_t relro_size;          /* Size of relro page(s) in bytes */
 150
 151     /* TLS information */
 152     int tlsindex;               /* Index in DTV for this module */
 153     void *tlsinit;              /* Base address of TLS init block */
 154     size_t tlsinitsize;         /* Size of TLS init block for this module */
 155     size_t tlssize;             /* Size of TLS block for this module */
 156     size_t tlsoffset;           /* Offset of static TLS block for this module */
 157     size_t tlsalign;            /* Alignment of static TLS block */
 158
 159     /* Items from the dynamic section. */
 160     Elf_Addr *pltgot;           /* PLT or GOT, depending on architecture */
 161     const Elf_Rel *rel;         /* Relocation entries */
 162     unsigned long relsize;      /* Size in bytes of relocation info */
 163     const Elf_Rela *rela;       /* Relocation entries with addend */
 164     unsigned long relasize;     /* Size in bytes of addend relocation info */
 165     const Elf_Rel *pltrel;      /* PLT relocation entries */
 166     unsigned long pltrelsize;   /* Size in bytes of PLT relocation info */
 167     const Elf_Rela *pltrela;    /* PLT relocation entries with addend */
 168     unsigned long pltrelasize;  /* Size in bytes of PLT addend reloc info */
 169     const Elf_Sym *symtab;      /* Symbol table */
 170     const char *strtab;         /* String table */
 171     unsigned long strsize;      /* Size in bytes of string table */
 172
 173     const Elf_Verneed *verneed; /* Required versions. */
 174     Elf_Word verneednum;        /* Number of entries in verneed table */
 175     const Elf_Verdef  *verdef;  /* Provided versions. */
 176     Elf_Word verdefnum;         /* Number of entries in verdef table */
 177     const Elf_Versym *versyms;  /* Symbol versions table */
 178
 179     const Elf_Hashelt *buckets; /* Hash table buckets array */
 180     unsigned long nbuckets;     /* Number of buckets */
 181     const Elf_Hashelt *chains;  /* Hash table chain array */
 182     unsigned long nchains;      /* Number of chains */
 183
 184     char *rpath;                /* Search path specified in object */
 185     Needed_Entry *needed;       /* Shared objects needed by this one (%) */
 186
 187     STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
 188                                                know about. */
 189     Ver_Entry *vertab;          /* Versions required /defined by this object */
 190     int vernum;                 /* Number of entries in vertab */
 191
 192     Elf_Addr init;              /* Initialization function to call */
 193     Elf_Addr fini;              /* Termination function to call */
 194
 195     bool mainprog : 1;          /* True if this is the main program */
 196     bool rtld : 1;              /* True if this is the dynamic linker */
 197     bool textrel : 1;           /* True if there are relocations to text seg */
 198     bool symbolic : 1;          /* True if generated with "-Bsymbolic" */
 199     bool bind_now : 1;          /* True if all relocations should be made first */
 200     bool traced : 1;            /* Already printed in ldd trace output */
 201     bool jmpslots_done : 1;     /* Already have relocated the jump slots */
 202     bool init_done : 1;         /* Already have added object to init list */
 203     bool tls_done : 1;          /* Already allocated offset for static TLS */
 204     bool phdr_alloc : 1;        /* Phdr is allocated and needs to be freed. */
 205     bool z_origin : 1;          /* Process rpath and soname tokens */
 206     bool z_nodelete : 1;        /* Do not unload the object and dependencies */
 207     bool z_noopen : 1;          /* Do not load on dlopen */
 208     bool ref_nodel : 1;         /* Refcount increased to prevent dlclose */
 209     bool init_scanned: 1;       /* Object is already on init list. */
 210     bool on_fini_list: 1;       /* Object is already on fini list. */
 211     bool dag_inited : 1;        /* Object has its DAG initialized. */
 212
 213     struct link_map linkmap;    /* For GDB and dlinfo() */
 214     Objlist dldags;             /* Object belongs to these dlopened DAGs (%) */
 215     Objlist dagmembers;         /* DAG has these members (%) */
 216     dev_t dev;                  /* Object's filesystem's device */
 217     ino_t ino;                  /* Object's inode number */
 218     void *priv;                 /* Platform-dependent */
 219 } Obj_Entry;
 220
 221 #define RTLD_MAGIC      0xd550b87a
 222 #define RTLD_VERSION    1
 223
 224 /* Flags to be passed into symlook_ family of functions. */
 225 #define SYMLOOK_IN_PLT  0x01    /* Lookup for PLT symbol */
 226 #define SYMLOOK_DLSYM   0x02    /* Return newest versioned symbol. Used by
 227                                    dlsym. */
 228
 229 /* Flags for load_object(). */
 230 #define RTLD_LO_NOLOAD  0x01    /* dlopen() specified RTLD_NOLOAD. */
 231 #define RTLD_LO_DLOPEN  0x02    /* Load_object() called from dlopen(). */
 232 #define RTLD_LO_TRACE           0x04    /* Only tracing. */
 233 #define RTLD_LO_NODELETE        0x08    /* Loaded object cannot be closed. */
 234
 235 /*
 236  * Symbol cache entry used during relocation to avoid multiple lookups
 237  * of the same symbol.
 238  */
 239 typedef struct Struct_SymCache {
 240     const Elf_Sym *sym;         /* Symbol table entry */
 241     const Obj_Entry *obj;       /* Shared object which defines it */
 242 } SymCache;
 243
 244 struct Struct_RtldLockState {
 245         int lockstate;
 246         sigjmp_buf env;
 247 };
 248
 249 void _rtld_error(const char *, ...) __printflike(1, 2);
 250 Obj_Entry *map_object(int, const char *, const struct stat *);
 251 void *xcalloc(size_t);
 252 void *xmalloc(size_t);
 253 char *xstrdup(const char *);
 254 void *xrealloc(void *, size_t);
 255 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
 256
 257 void dump_relocations(Obj_Entry *);
 258 void dump_obj_relocations(Obj_Entry *);
 259 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
 260 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
 261
 262 /*
 263  * Function declarations.
 264  */
 265 const char *basename(const char *);
 266 unsigned long elf_hash(const char *);
 267 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
 268   const Obj_Entry **, int, SymCache *);
 269 void init_pltgot(Obj_Entry *);
 270 void lockdflt_init(void);
 271 void obj_free(Obj_Entry *);
 272 Obj_Entry *obj_new(void);
 273 void _rtld_bind_start(void);
 274 const Elf_Sym   *symlook_obj(const char *, unsigned long, const Obj_Entry *,
 275   const Ver_Entry *, int);
 276 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
 277 struct tls_tcb  *allocate_tls(Obj_Entry *);
 278 void free_tls(struct tls_tcb *);
 279 void *allocate_module_tls(int index);
 280 bool allocate_tls_offset(Obj_Entry *obj);
 281 void free_tls_offset(Obj_Entry *obj);
 282 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
 283
 284 /*
 285  * MD function declarations.
 286  */
 287 int do_copy_relocations(Obj_Entry *);
 288 int reloc_non_plt(Obj_Entry *, Obj_Entry *);
 289 int reloc_plt(Obj_Entry *);
 290 int reloc_jmpslots(Obj_Entry *);
 291 void allocate_initial_tls(Obj_Entry *);
 292
 293 #endif /* } */